There are numerous examples of existing structures being replaced by lighter weight materials. For example, fiber reinforced resins, also known as composite materials, have replaced wood structures in sporting good applications such as golf clubs, tennis racquets, hockey sticks and baseball bats. Composite materials have also been used to replace metal in similar applications such as golf clubs, tennis racquets, skis, and bicycle frames.
Preferably, the lightest materials and designs are used to achieve the performance goals of the particular structure. The most popular high performance material for modern structure design is carbon fiber reinforced epoxy resin (CFE) because it has the highest strength and stiffness to weight ratio of any realistically affordable material. As a result, CFE can produce a very light weight structure with excellent strength as well as providing a variation of stiffness at various regions along the surface or length of the structure.
However, there are limitations on carbon fiber based materials used for structures when considering strength requirements. For example, a tubular structure made from a carbon fiber composite can be susceptible to catastrophic failure resulting from excessive compressive forces, which can cause buckling of the thin walled tubes. The tubular structure may also be subjected to a multitude of stress conditions, for example, transverse impact loads, torsional loads or vibrational loads. A thin walled tube made of a fiber reinforced composite may not have the strength to withstand various loading condition scenarios.
Also, in the prior art, if holes were required in a hollow structure, for example, to reduce weight or for fastening means or for aerodynamics, the holes would be formed by removing material by cutting or drilling holes in the walls of the structure. This weakens the structure considerably when reinforcing fibers are severed during the cutting of the holes.
Thus, there exists a continuing need for an improved structure that has the combined features of light weight, improved bending, improved stiffness, improved vibration damping, improved aerodynamics, and improved aesthetics.